Plastic explosive and method of making it



3,949,453 Patented Aug. 14, 1962 3,049,453 PLASTIC EXPLOSIVE AND METHOD OF MAKING IT Paul Ren De Wilde, Geneva, Switzerland, assignor of one-half to Societe Suisse des Explosifs, Gamsen, near Brigue, Valais, Switzerland No Drawing. Filed Mar. 28, 1960, Ser. No. 17,749 Claims priority, application Switzerland July 13, 1959 3 Claims. (Cl. 14920) During the years 1935-4939 there have been manufactured considerable quantities of an explosive consisting of a mixture of ammonium nitrate and at least one nitrate of an alkylamine. This manufacture has been abandoned because this explosive, in spite of its being easily made in great quantities and in spite of its being inexpensive and of stable nature, has the property of being hygroscopic. This circumstance, of course, does not permit its storing, except in watertight containers, because otherwise it would attract such quantites of water that its capability of becoming detonated would decrease to a point where the transmission of explosive waves from one charge to another would disappear, especially where the charges are of calibres below 30 mm.

Research carried out during the last years in explosives which contained considerable quantities of water have shown that when there is incorporated in an explosive of the kind indicated a sufficiently powerful explosive substance with a great velocity of detonation, there is reached an absolute certainty of transmitting the explosive wave in the explosive mixture to usually required distances, this being the case even with calibres below 30 mm, and even where the explosive mixture contains up to 10% by weight of water.

This discovery, together with the fact that a mixture of ammonium nitrate (or any other alkali metal nitrate or alkaline earth nitrate) with nitrates of an alkylamine and a small percentage of water results at ambient temperatures in a plastic and more or less fluid consistency, makes it possible to prepare explosives of plastic consistency which possess excellent explosive qualities. The explosives are as powerful as the currently used explosives in the form of jellies and they are safe as far as their properties relative to water are concerned.

The present invention is based on this discovery and concerns an explosive of plastic consistency and the method of its manufacture.

The explosive according to the invention is constituted by a dispersion of a solid explosive of great velocity of detonation in a pasty mass comprising an alkali nitrate or alkaline earth nitrate and a nitrate of an alkylamine and water.

This explosive may advantageously contain from 8 to 25% by weight of the said solid explosive of great velocity of detonation such as that known under the commercial name Penthrite (nitropentaerythrite), or that known under the name Hexogene (cyclotrimethylenetrinitramine) and between to 15% by weight of water. The alkali nitrate or alkaline earth nitrate may be ammonium nitrate and the nitrate of an alkylamine may be the nitrate of triethanolamine.

This novel plastic explosive has a density substantially equal to that of ordinary gelatinous dynamites but has the advantage that it does not contain any nitric esters in liquid form and that it can be prepared by simply mixing its constituents.

The manner of making the new explosive, which is also one of the subject matters, of the present invention,

comprises the step of preparing an intimate mixture of an alkali nitrate or an alkaline earth nitrate with a nitrate of an alkylamine and water, the quantity of the latter being such that the mixture becomes pasty, and the step of dispersing in this mixture a solid explosive substance of high velocity of detonation in finely divided state.

This novel plastic explosive has special advantages for use in galleries of mines over other plastic explosives containing a rather high percentage of liquid nitric esters and being more or less jellified by soluble nitrocellulose. This advantage resides in the fact that the gases result ing from the explosion still contain a certain quantity of free oxygen which-small as it might be-prevents these gases from containing carbon monoxide, the action of which might be extremely harmful to miners.

This explosive shows, as a consequence of the contents of an a1kylamine-and ammonium nitrates-a tendency to absorb ambient humidity which in the long run might be disadvantageous to the certainty of the explosibility.

It has also been found that the addition of even a small quantity of a jellifying agent, such as a glucosidc, suppresses the property of attracting humidity from the air and that thereby a certain aqueous dilution of the nitrates is attained which will not increase subsequently.

Tests have shown that the explosive, when it contains some percents of water, 67% of an alkylamine nitrate and approximately 1% or even less of glucoside, does not attract practically any water when it is left in moist air even during several days. A certain equilibrium appears to be established between the hygroscopicity of the said nitrate and the vapor tension of their solution in the explosive. This equilibrium comes about even in the presence of great quantities of ammonium nitrate.

This remarkable property of the jellifying agent imparts to the explosive according to the invention a resistance to humidity which in practice is fully sufiicient and which is the same as that of ordinary dynamite jellies based on ammonium nitrate.

This explosive, according to the invention, in its most advantageous composition, is constituted by a dispersion of a solid explosive of great detonative velocity in finely divided form in a pasty mass formed at least partially by a water soluble jellifying agent, by at least an alkali or alkaline earth nitrate, by at least an alkylamine nitrate, and by water.

This explosive can be manufactured according to the process which forms part of the invention, by preparing an intimate mixture of a water-soluble jellifying agent, at least one alkali or alkaline earth nitrate, at least one alkylamine nitrate and water, the quantities of the latter and of the said agents being such that the mix becomes pasty, adding to the mixture a solid explosive substance of great detonative velocity in finely divided form, this latter being dispersed in the said mixture.

In the manufacture, it is no more necessary to dry the various components. It is fully suflicient to know the degree of humidity of every one of them and to regulate the aqueous dilution as it is desired for the alkylamine nitrate in accordance with the presence of water derived from the other, humid starting materials.

The absolute absence of liquid nitric esters constitutes a great progress in the art from the point of view of general safety of manufacture and safety in the manipulation as well as from an hygienic point of view. This latter point is of importance with regard to the personnel in the manufacturing plants, as well as regards the miner who eventually uses the new explosive.

As to the latter, they are not liable to suffer any more in t up from the current illnesses caused by hitherto used explosives, such as headaches, cyanosis, manifestations due to certain idosyncrasies, symptoms of poisoning and the like. All these manifestations common in the manipulation of plastic dynamite on the basis of liquid nitric esters are no more experienced.

The explosives according to the invention, due to their water contents, are difficulty inflammable, in any case less so than ordinary plastic dynamite under equal conditions.

Their water contents in relation to the alkylamine nitrates imparts to these explosives the property of not becoming solid by freezing and remaining plastic even at very low temperatures, i.e., below 20 C.

The following illustrative examples which are not intended to limit the invention thereto, show how the invention may be carried into effect. The first two of these examples relate to the manufacture of the explosive according to the invention and the two latter examples indicate the compositions and the properties of explosives according to the invention, containing a jellifying agent.

EXAMPLE 1 15 parts of a 50% aqueous solution of triethanolamine nitrate are mixed with 65 parts by weight of ammonium nitrate and the pasty mix is kneaded to complete homogeneity. Thereupon are added 20 parts by weight of nitropentaerythrite in crystalline form, the crystals being of a size smaller than 0.25 mm.

The so-obtained plastic mass having about the consistency of glaziers putty can easily be filled in cartridges, just as ordinary plastic dynamite.

Instead of nitropentaerythrite or hexogene, there may be used a mixture thereof with other nitric derivatives of high detonative speed. There may be incorporated in the explosive certain metallic powders, such as aluminum so as to increase the temperature of the explosive gas and thereby its force.

EXAMPLE 2 There is prepared an aqueous solution of an alkylamine nitrate and a jellifying agent, the water contents of the solution being in accordance with that of the other constituents, so that the final explosive containes e.g. between 5 and by weight of water. Then, there is added to this solution first an alkali nitrate (e.g. a mmonium) or an alkaline earth nitrate and then the solid explosive substance of great detonative speed in form of small crystals, in such quantities that the final explosive contains 15 to 25%. In this way there is obtained an explosive of good plasticity and of sufiicient resistance to atmospheric humidity.

With such an explosive the transmission in the air of an explosive wave from one charge to another is certain: between cartridges of 30 mm. diameter at distances of 2 cms. end to end; with cartridges of 25 mm. at distances of 1 cm. end to end; for cartridges of 22 mm. diameter, the distance from end to end must be less than 1 cm. and their contents of an explosive with high detonative speed should be at least of their weight.

This relatively low sensitivity to free air increases if the operation is carried on in confined spaces or in closed cavities, e.g., in a bore-hole. It is in any case sufiicient for every ordinary mining operation.

4 EXAMPLE 3 Brisant Plastic Explosive Percent by weight Ammonium nitrate 64.5 Diethanolamine nitrate 8 Water 3 Aluminum powder 4 Carob bark extract, dry 0.5

Nitropentaerythrite in crystals of about 0.25 mm 20 This explosive gives a clean excavation in a Trautzl block of 410 cmfi, its density in the cartridge being 1.38; its oxygen balance is positive+0.5%. The transmission in free air of the explosive wave is certain at distances of 20 mm. between cartridges of 30 mm. diameter; it becomes uncertain at distances from 25 mm. upwards.

EXAMPLE 4 Less Brisant Explosive Than That of Example 3 Percent by weight Ammonium nitrate 66.5 Triethanolamine nitrate 9 Water 4 Carob bark extract, dry 0.5 Nitropentaerythrite 20 This explosive gives a clean excavation in a Trautzl lock of 375 cm. its density in the cartridges being 1.35; its oxygen balance is positive+1%; the transmission of an explosive wave in free air is of the same order as that a of Example 3.

What I claim is:

1. An explosive of plastic consistency, consisting essentially of 20 parts by weight of nitropentaerythrite, parts by weight of ammonium nitrate, 7.5 parts by weight of ethanolamine nitrate, 7.5 parts by Weight of water, and 0.5 part by weight of carob bark extract, said nitropentaerythrite being finely dispersed in a pasty mass of said other components.

2. An explosive of plastic consistency consisting essentially of 8 to 25% by weight of a solid explosive substance of great detonative velocity selected from the group consisting of nitropentaerythrite and hexogen, a large amount of ammonium nitrate, a minor amount of a water soluble gelling agent selected from the group consisting of glucosides, and carob bark extract, at least one compound taken from a group consisting of alkylamine nitrate selected from the group consisting of monoethanolamine nitrate, diethanolamine nitrate and triethanolamine nitrate, and 5 to 15% by weight of water, said solid explosive substance of great detonative velocity being finely dispersed in a pasty mass of said other components.

3. An explosive according to claim 2 containing further oxidisable aluminum metal powder dispersed in the pasty mass.

References Cited in the file of this patent UNITED STATES PATENTS 2,063,572 Woodbury et al. Dec. 8, 1936 2,455,205 Whetstone et al. Nov. 30, 1948 2,860,041 Griffith et al. Nov. 11, 1958 

1. AN EXPLOSIVE OF PLASTIC CONSISTNECY, CONSISTING OF ESSENTIALLY OF 20 PARTS BY WEIGHT OF NITROPENTAERYTHRITE, 65 PARTS BY WEIGHT OF AMMONIUM NITRATE, 7.5 PARTS BY WEIGHT OF ETHANOLAMINE NITRATE, 7.5 PARTS BY WEIGHT OF WATER, AND 0.5 PART BY WEIGHT OF CAROB BARK EXTRACT, SAID NITROPENTAERYTHRITE BEING FINELY DISPERSED IN A PASTY MASS OF SAID OTHER COMPONENTS. 